For architectural laminated glass, automobile windshield, and the like, generally, a multilayer structure articles having a function, that is, pieces of glass are not scattered when the glass is broken, or people, things, and the like do not rush outside penetrating the glass, which is obtained by arranging a film of polyvinyl acetal resin or the like between two inorganic glasses or organic glasses, and then by performing heating and pressure laminate, is used. Further, as to a solar cell module, it has been performed widely that solar cells (crystalline silicon, thin-film silicon, a metal compound thin film, an organic thin film, and a transparent or opaque electrode layer) are arranged between two glasses or weather-resistant plastic films, and a film of polyvinyl acetal resin and the like is arranged between the cells and the glasses on both sides of the cells, and then for which the film is melted to flow to fill up the gap by heating and crimping the entire resultant. However, when such a multilayer structure articles is produced, air bubbles are generated at the edge portion of the polyvinyl acetal resin layer, or unfilled portion of the polyvinyl acetal resin is generated in the structure, as a result, there may become a defective product.
In order to solve these problems, for example, as disclosed in Patent Literature 1, Patent Literature 2, and Patent Literature 3, as to a filler, there have been proposed a method in which the degassing is made easier by providing emboss on the surface, or by optimizing the creeping property, and the like. Further, in Patent Literature 4, there have been proposed a method in which the shape of the edge portion of glass is defined to make the degassing easier, and not to generate the unfilled portion.
Furthermore, as to the heat shrinkage of a sheet or film containing polyvinyl acetal resin, there are descriptions in Patent Literature 5, Patent Literature 6, and Patent Literature 7. Specifically, in Patent Literature 5, there are descriptions that as an attempt to impart degassing performance at the time of lamination, and impact resistance of laminated glass, an interlayer film for laminated glass in which the difference in shrinkage in respective portions is within ±1% is used, and further that the shrinkage when the interlayer film is heated at 54° C. for 10 minutes is about 2%. In Patent Literature 6, there are descriptions that as an attempt to obtain a specific film that is particularly useful as an intermediate layer for laminated glass in curved windshield, a film shape object of polyvinyl acetal resin showing a positive rate of change in the shrinkage is used, and further that the shrinkage when the film is heated at 71° C. for 30 minutes is about 5 to 13%. In Patent Literature 7, there are descriptions that as an attempt to reduce the variations in thickness of sheet due to strain, or to reduce the heat shrinkage, an embossed sheet in which emboss having a specific shape is formed is used, and further that the shrinkage when the sheet is heated at 50° C. for 10 minutes is about 2.5%.